ASVAB Shop Information study guide

What this subtest actually asks of you

Shop Information is 10 of the 135 scored questions on the computer ASVAB — 7% of the scored test. Like Auto Information, it is not one of the four AFQT subtests, so it does not move the number that decides whether you can enlist — but it does feed the line scores that decide which jobs you qualify for (how the ASVAB is scored). On the paper form Shop Information and Auto Information are reported as one combined score; the computer test asks them as two separate subtests of 10 questions each, and that is the split this site follows.

Almost all of it is recognition: which tool does which job, which fastener or material belongs in a given situation, and which way of working is the safe one. There is nothing to calculate except reading a measurement or converting a size.

Two consequences:

• Learn the jobs, not a tool list. Every tool belongs to a job family — measure, hold, turn, cut, drill, drive, shape, join — and the family tells you what the tool does even when its name is new to you.
• Learn every tool with its material attached. "A hacksaw cuts metal; a crosscut saw cuts wood." The favorite wrong answer on this subtest is the right tool for the wrong material, so the boundary is worth more than the definition.

The tool map: how to place a tool you have not met

When a question names a tool you cannot picture, ask which job it must belong to, then which material that job is being done to. That pair of answers eliminates most of the choices before you know anything else about the tool.

Measure and lay out

Hold and turn

Cut wood

Cut metal

Drill and thread

Drive and strike

Shape and smooth

Join

Stay safe

Wire

Plumb

Know the material

Every question on this subtest is answered out of those tables plus the material the job is being done to. If you can name the job family a tool belongs to, you can usually strike out half the choices immediately.

The one picture worth keeping: four jobs, four tools

Every tool on this subtest is built for exactly one of four moves: measuring something, turning a fastener, cutting a material, or striking a blow. Learn the move and you can place the tool — and you can also see why a tool fails at a job it was not built for.

Read the four panels as one rule: the shape of a tool is its job. A rule is marked in small divisions because its job is fine measurement; a jaw is six-sided because a bolt head is; a blade is a row of teeth because cutting is a series of small chips; a hammer has a flat face and a hook because it has to both drive and remove. When a question offers you a tool whose shape does not match the job in the stem, that tool is the wrong answer.

The four-step method for a tool you cannot recall

1. Name the job in the question. "That is a measuring question" or "that is a fastening question" — naming the job usually removes two choices before you know anything about the tool itself.

2. Name the material. Wood, metal, masonry, sheet metal, pipe, drywall, concrete. A wood chisel and a cold chisel are both chisels and only one of them survives being driven into steel; a twist bit and a masonry bit are both drills and only one of them is built for brick. The material decides the answer more often than the tool's name does.

3. Eliminate the neighbor. The favorite wrong answer is the tool from the next job over: the pipe wrench offered where an adjustable wrench belongs, the rip saw offered for a crosscut, the single-cut file offered where a fast cut is wanted. If two choices are a known pair, the question is about the boundary between them — the confusables table below is for exactly that call.

4. For "what happens if" questions, follow the chain one step. Every one of these asks a single physical consequence, and the consequence follows from the tool or the material, not from a rule you have to have memorized:

• A dull blade forces you to push harder, and a hard push that binds is what turns into kickback.
• A 14-gauge wire on a 20-ampere breaker overheats before the breaker trips, because the breaker is set for a wire one size larger than the one it is protecting.
• A screw driven into hardwood with no pilot hole pushes the grain apart instead of cutting into it, and near the end of the board there is not enough wood left to absorb the push, so the board splits.
• A pressure-treated board fastened with plain steel nails corrodes the nails from the inside out, and the joint that was tight on the day it was built comes loose years later.

The confusables

Each line is a boundary this subtest is built on. Two choices from one row means the question is about that boundary.

The core facts, by idea

Measuring and layout. A micrometer closes a spindle onto the part against a fixed anvil; the thimble scale reads the gap to the nearest thousandth of an inch, one full turn of the thimble moves the spindle 0.025 in, and the thimble is divided into 25 marks of one thousandth each. A steel tape reads length along a surface, and the smallest mark on an ordinary tape is 1/16 in. A try square checks a 90-degree corner, a level reads whether something is horizontal, and a plumb bob hangs on a string to show whether a post is vertical. A chalk line snaps a long straight line across a sheet too wide for any square, a feeler gauge measures a narrow gap with thin steel leaves of a known thickness, and a dial caliper measures inside, outside and depth in one tool.

Cutting wood. A crosscut saw has many small teeth and cuts across the grain; a rip saw has fewer, larger teeth and cuts along it. Saw teeth are set — bent slightly left and right — so the blade's track is wider than the plate, and that width is the kerf. On a circular saw the blade should project only about one tooth below the work, and the work should be supported so the cut cannot close on the blade. A table saw is fed with the work moving past a fixed blade, a circular saw with the blade moving through fixed work: fence for ripping, miter gauge for crosscuts, never both at once, and a push stick for anything narrow. A dull blade is the more dangerous one, because you push harder and a hard push is what binds and kicks back.

Cutting metal. A hacksaw blade cuts on the push stroke, so its teeth point away from the handle. Match the teeth to the wall thickness: about 32 teeth per inch for thin tubing, 18 or 24 for thick stock, because a coarse blade lets its teeth straddle a thin wall and tear it. Tin snips cut sheet metal, bolt cutters cut rod and chain, an angle grinder cuts and grinds, and a cold chisel shears metal while a wood chisel would be ruined by it. A file cuts on the push stroke too: hold the handle, keep the blade flat, and lift it on the return.

Drilling, tapping and threading. A center punch leaves a small dent so the bit starts where you marked instead of skating across smooth metal. A pilot hole about the diameter of the screw's core gives the shank somewhere to go, which is what keeps a screw from splitting a board near its end. A countersink cuts a tapered seat so a head finishes flush. Use a twist bit for metal, a spade or auger bit for wood, a masonry bit for concrete and brick, and a hole saw for a large hole. A tap cuts threads inside a hole, a die cuts them on the outside of a rod, and neither is a reamer: a reamer only trues a hole that has already been drilled.

Turning fasteners. Match the wrench to the head. An open-end wrench and a box-end wrench take hex nuts and bolts, an adjustable wrench fits a range of them at the cost of some slop, and a socket on a ratchet is the fastest way round a job with room to swing. A six-point socket bears on the six flats of the head, which is what you want on a rusty or damaged fastener; a twelve-point socket reaches into a tighter space but grips the corners and rounds them off. A pipe wrench is the one tool for round pipe: its serrated jaws bite in one direction only, so force tightens the grip instead of slipping. A torque wrench measures the turning force as it tightens and is not used to loosen a fastener, which can affect its calibration — use a breaker bar for that. Allen keys turn hex-socket screws, a Torx driver turns a six-pointed star, a Phillips driver turns a cross and is built to cam out rather than strip the head, and a flat-head screwdriver turns a single straight slot. A screwdriver is never a chisel, a pry bar or a punch. A standard right-hand thread tightens clockwise, and that is what you will meet on nearly every fastener; a left-hand thread tightens the other way, which is why the left pedal on a bicycle and some gas fittings turn backward.

Driving, holding and striking. A claw hammer drives with its face and pulls nails with its curved claw; a ball-peen hammer has a round end that works metal — peening a rivet, striking a punch or a cold chisel; a mallet in wood, rubber or plastic strikes a wood chisel or a soft assembly without leaving a mark; and a sledge is for the heaviest blows. Locking pliers clamp shut and stay shut once squeezed, so both hands are free for a wrench on the other side of the joint, while needle-nose pliers reach small parts in a tight space and lineman's pliers combine a heavy cutter with a gripping jaw for wire. Diagonal cutters cut wire, tin snips cut sheet metal, and a pry bar does the prying that a screwdriver or a wrench must never be asked to do.

Fasteners and the joints they make. Choose the fastener by what the joint has to survive. A nail holds by friction, is driven in one blow and pulls out under a steady load; a screw grips with threads, resists being pulled out, and can be taken apart again. Nail size is given in penny numbers, where a 16-penny nail is 3-1/2 inches long and an 8-penny is the general-purpose 2-1/2 inches, while a finishing nail carries a small head that is set below the surface and filled so trim shows no mark. A drywall screw has a bugle head that crushes a shallow dimple in the board so the head sinks just below the surface for joint compound. A machine bolt with a nut clamps two steel plates together by drawing them, not by threading into the steel. A lag screw bites into solid wood; a toggle bolt folds its wings through a hole and opens them behind a hollow wall; a plastic or expanding anchor does the same job in masonry. A flat washer spreads the load of a head over a wider area, a lock washer resists loosening under vibration, and a rivet joins sheet metal permanently where nothing will ever need to come apart.

Materials. Lumber is named by the size it was sawn to, not the size it is: the rough board is planed smooth on all four sides after sawing, so a 2 by 4 measures 1-1/2 by 3-1/2 inches. Hardwood is bought by the board foot, which is 12 inches wide, 12 inches long and 1 inch thick — 144 cubic inches of wood, a volume, not a shape. Plywood is thin veneer layers glued with their grain at right angles, layer to layer, which is why a sheet stays flat where a wide solid board cups and twists as humidity changes. Medium-density fiberboard is wood fiber pressed with resin into a uniform sheet with no grain and no voids, so a cut or routed edge comes out smooth and takes paint evenly; particle board is the coarser cousin made from chips. Pressure-treated wood carries copper-based chemicals that corrode plain steel, so it takes galvanized or stainless fasteners. Sheet metal is sized by gauge, and as with wire, a higher number is thinner. Pipe is copper where it is soldered or crimped rigid, PVC where it is solvent-welded plastic, and PEX where it is flexible and crimped.

Joining and adhesives. Wood glue is stronger than the wood itself on a well-fitted joint; epoxy fills gaps and bonds metal, glass and plastic where glue cannot; contact cement is for laminating a sheet onto a panel; and construction adhesive sticks panels to framing so they stop squeaking. Mechanical alignment comes from dowels, biscuits and joints with names worth knowing: a miter cuts the end of a board at an angle, a dado cuts a channel across the grain, and a rabbet cuts a step along an edge. Welding melts the two pieces together with filler metal from the same family; soldering melts only a low-temperature filler and uses flux to clean the joint, which is why soldering is the right choice for electrical work and welding is the right choice for structure.

Safety. Safety glasses with side shields are the first item on every list, because a chip comes off a chisel or a grinder sideways. Add a face shield for grinding, hearing protection for anything loud enough to make you raise your voice, a dust mask or respirator for sanding and finishing, and gloves where chemicals or sharp edges are the hazard — never where they can be caught by a spinning tool. Unplug the tool, or pull its battery, before changing a blade or a bit, and wait for it to stop. Keep every guard in place, use a push stick rather than your fingers near a blade, clear chips with a brush instead of your hand or compressed air, and keep the floor clear. A sharp tool is safer than a dull one, because it cuts where you aim instead of needing force.

Electrical in the shop. The breaker protects the wire, so the wire has to carry what the breaker allows: 14-gauge copper carries 15 amperes and 12-gauge carries 20 amperes. A higher gauge number is a thinner wire carrying less current, which is the single fact most of these questions turn on. A wire nut joins two or more conductors and insulates the joint, wire strippers remove insulation without nicking the copper, a multimeter reads volts, amps and continuity, and a GFCI outlet is the device that protects a person rather than the wiring by tripping on a small current leaking to ground.

Plumbing in the shop. Copper pipe is joined by soldering or crimping, PVC with solvent cement, and PEX with a crimp ring or a push fitting. Fittings do one job each: a coupling joins two lengths in a straight run, an elbow turns a run, a tee adds a branch, and a cap closes an end. Threaded joints are sealed with Teflon tape or pipe dope, a tubing cutter squares a pipe end before anything is fitted to it, and the curved trap under a sink holds a plug of water that keeps sewer gas from coming up the drain.

How to practice this

• Work the free Shop Information practice set with the tool map in front of you. Read the tool name, place it in a job row, name the material, then predict the answer before you look at the choices.
• Learn the pairs in the confusables table as pairs. On this subtest the pairs are the questions: tap against die, claw hammer against ball-peen hammer, flat washer against lock washer, 14-gauge against 12-gauge.
• Carry one sentence per tool: what it does, and what it is made of or made for. A hacksaw cuts metal, a crosscut saw cuts wood across the grain, a cold chisel shears metal, and a wood chisel would be ruined by it.
• Read the explanation on every question, including the ones you got right — the reason a wrong choice is wrong is usually the exact boundary you were fuzzy on.

The other half of this subtest's trade is the Auto Information guide — the parts, the systems and the four-stroke cycle. How to study for the ASVAB has the rest of the method, and what the pass adds.

Where to go next

• Next topic — Mechanical Comprehension
• The exam itself — how the ASVAB is scored, how many questions, and what makes the ASVAB hard.

Shop Information carries 10 of the 135 scored questions on the computer test, where it is administered as one half of Auto & Shop Information and reported with the other half as a single score — and the AFQT score is not computed from it: that score comes from Arithmetic Reasoning, Mathematics Knowledge, Word Knowledge and Paragraph Comprehension.

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